Foundation Integrity

Ensuring Pile Fitness for Purpose

In a basic sense, piles are deep foundations and are made up of concrete or steel and shaped in long cylinders or columns. These piles inherently support a building. Within this subject there are various technicalities, such as type of pile, purpose, load variations and the material used in its construction. However, what can be stated is that regardless of these various defining factors it is absolutely vital that piles are fit for purpose.

HOKLAS foundation integrity testing incorporates the pile integrity test (PIT) which at its root is a loading test. Because piles are used to transfer load to firmer ground, which is particularly necessary where subsoil conditions are weak for example, testing of piles is intrinsically linked to this subsoil layer too. Therefore, structural integrity of the actual pile needs to be assured and this is connected to the soil conditions.

Traditionally, this type of foundation integrity testing was carried out via excavation around a pile, as well as more intrusive methods which often included core drilling. The issue here was the time and expense in carrying out such procedures.

Today, HOKLAS foundation integrity testing methods in this area are far more efficient in identifying which piles require a load test and which do not. In essence, PIT is a way to quickly make a call on the performance of many piles and behaviour individually and as a whole. As well as integrity, this type of evaluation is often used to detect the quality of piles and even to clarify the length of piles and foundations that are already in existence.

So, what is PIT? The pile integrity test is a non-destructive test which is highly advantageous in terms of time and cost as well as disruption of a construction project. The low strain testing method is used on a test pile, and in effect compression waves are measured, with waves reflecting where issues are detected. Problems can include voids or potential changes in the diameter of a pile.

As well as the PIT, the pile driving analyser (PDA) is another way to test foundation integrity. Hammer blows at the top of the pile are measured using this specialised equipment that works out the stress on the test pile, the force or energy of the hammer blow, and the bearing capacity of the load. Where concrete piles are already set, sonic logging can be used to detect any defects.